Frp-bamboo winding pipe multiple constraint geopolymer concrete column and preparation method thereof
By employing a multi-constraint structure of lithium slag geopolymer concrete and continuously directional wound bamboo-wound pipes with FRP composite layers, the problems of high carbon emissions, insufficient uniformity of constraint, and brittle failure in existing technologies have been solved. This has resulted in a high-efficiency, low-carbon, multi-constraint concrete column, which improves load-bearing capacity and ductility and is suitable for bridges, houses, and precast components.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HUNAN UNIV
- Filing Date
- 2026-04-09
- Publication Date
- 2026-06-23
AI Technical Summary
In existing technologies, core concrete is still mainly made of cement-based materials, which has high carbon emissions. The molding process of bamboo reinforcement layer has insufficient circumferential constraint uniformity and continuity, and the complex structural interface leads to low constraint transfer efficiency. There is a lack of direct, continuous and synergistic multiple constraint mechanisms between FRP and bamboo, making it difficult to simultaneously meet the requirements of low carbon, load-bearing capacity, ductility and green building.
Using lithium slag geopolymer concrete as the core, a multi-constraint structure is formed by continuously directional winding bamboo winding pipes and FRP composite layers. The lithium slag geopolymer concrete reduces carbon emissions, and the bamboo winding pipes are closely bonded to the FRP fiber cloth to form a circumferential synergistic force, achieving a multi-constraint effect.
It significantly improves the axial compressive bearing capacity and ductility of geopolymer concrete columns, reduces carbon emissions, enhances structural safety and reliability, balances economy and performance, achieves a progressive failure mode, and is suitable for bridges, houses and precast components.
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Figure CN122257553A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of structural engineering materials, specifically to an FRP-bamboo-wound tube multi-constrained polymer concrete column and its preparation method. Background Technology
[0002] With the deepening of green building and sustainable development, the demand for low-carbon, high-performance structural materials in the civil engineering field is becoming increasingly urgent. While traditional reinforced concrete columns are widely used, they suffer from problems such as heavy weight, susceptibility to corrosion, and insufficient ductility. Furthermore, the high carbon emissions from cement production make it difficult to meet the "dual carbon" targets. Against this backdrop, geopolymer concrete, due to its advantages such as utilizing industrial solid waste and low carbon emissions, has become an important direction for replacing cement-based materials. However, geopolymer concrete generally suffers from inherent defects such as high brittleness, poor crack resistance, and slow strength development, requiring external constraint structures to improve its mechanical properties.
[0003] Fiber-reinforced polymers (FRPs) are widely used to confine concrete columns due to their lightweight, high strength, and corrosion resistance. However, single FRP pipes are expensive, and their failure mode is mostly brittle fracture, with limited improvement in ductility. Bamboo, as a widely available, renewable, and mechanically excellent natural material, can be combined with FRP to form a multi-constraint structure, which holds promise for reducing costs and carbon emissions while maintaining load-bearing capacity. Researchers have already conducted relevant explorations in this area.
[0004] For example, CN106760215A discloses a fiber-bamboo composite pipe concrete structure, which uses an FRP layer and a bamboo reinforcement layer to confine the core concrete, utilizing the green characteristics of bamboo and the high strength of FRP. However, its bamboo reinforcement layer is a composite of longitudinal and transverse lay-ups, and is formed by discontinuous directional winding, resulting in insufficient uniformity and continuity of circumferential confinement; at the same time, the core concrete is still a cement-based material, and does not use geopolymer concrete, resulting in higher carbon emissions.
[0005] CN118208002A discloses a thin-walled composite material-bamboo plywood tube confined concrete composite column, which forms a multi-layer composite structure with FRP tubes, an intermediate concrete layer, and bamboo plywood tubes, resulting in high construction efficiency. However, the intermediate concrete layer filling the gap between the FRP tubes and bamboo plywood tubes increases the number of interfaces, making relative slippage or delamination more likely and reducing the confinement transfer efficiency. Furthermore, the core concrete is still a cement-based material, and the bamboo is plywood tube rather than a continuous fiber-wound tube, limiting its green and low-carbon development level.
[0006] CN115822175A discloses a composite confined concrete composite column consisting of a composite tube and a bamboo cage, which uses a bamboo cage and composite tube to form a composite confined structure, resulting in low cost and good overall integrity. However, the bamboo cage is made using a hand-woven process, and the strength of the circumferential bamboo strips is low and the dispersion is large, making it difficult to ensure a uniform and stable circumferential confining effect; the core concrete is also a cement-based material, and geopolymer concrete is not used.
[0007] CN110700492A discloses an ecological composite column containing recycled concrete from solid waste, which combines recycled concrete, glued bamboo board layers, and FRP to achieve formwork-free construction and solid waste utilization. However, its cementing material is still mainly cement, resulting in limited carbon emission reduction; the bamboo material is a glued bamboo board layer (laminated), rather than a continuously oriented wound bamboo tube, resulting in weak circumferential constraint; at the same time, the introduction of the inner lining ring makes the structural interface complex, making it difficult to achieve efficient multi-constraint through direct composite of FRP and bamboo tube.
[0008] In summary, the existing technology has the following problems in this field:
[0009] (1) The core concrete is still mainly cement-based materials, which have high carbon emissions and do not fully utilize the low-carbon advantages of geopolymer concrete. In the existing technology, whether ordinary concrete, micro-expansion concrete or recycled concrete is used, cement is the main cementitious material. There is a lack of application of alkali activation of industrial solid waste (such as fly ash, slag, etc.) to prepare geopolymer concrete, which makes it difficult to achieve low-carbon structure.
[0010] (2) The forming process of bamboo reinforcement layer is mostly lay-up, gluing or weaving, which is insufficient in terms of uniformity and continuity of circumferential constraint. In the existing technology, bamboo reinforcement layer is mostly formed by longitudinal and transverse lay-up composite, bamboo plywood tube or bamboo woven cage, etc., which are all non-continuous directional winding forming, resulting in uneven distribution of circumferential constraint force and large strength dispersion, making it difficult to provide a stable and reliable multi-constraint effect.
[0011] (3) The complex structural interface results in low constraint transfer efficiency and makes it prone to slippage or peeling failure. For example, in CN118208002A, an intermediate concrete layer is filled between the FRP pipe and the bamboo plywood pipe, and in CN110700492A, an inner lining ring is set. Both of these increase the number of interfaces, weaken the direct bonding synergy between FRP and bamboo, and make it difficult for the multiple constraint mechanisms to be fully utilized. The failure modes are mostly brittle or non-synergistic failure.
[0012] (4) There is a lack of direct, continuous and synergistic multiple constraint mechanisms between FRP and bamboo. In the existing technology, there is often an isolation layer or discontinuous interface between the FRP layer and the bamboo layer. The optimized constraint mode of strong bonding between the FRP composite layer and the bamboo winding tube through the resin adhesive layer, circumferential synergistic stress, and progressive failure has not been achieved. The ductility improvement effect is limited, and it is difficult to simultaneously meet the comprehensive requirements of load-bearing capacity, ductility and green low carbon.
[0013] Therefore, developing a multi-constrained concrete column with geopolymer concrete as the core, continuously oriented wound bamboo tubes as the inner constraint, and FRP as the outer constraint, with direct bonding between the layers to share the load, has become a technical problem that still needs further optimization in this field. Summary of the Invention
[0014] Based on the problems existing in the above-mentioned background technology, the present invention proposes an FRP-bamboo wound tube multi-constrained polymer concrete column and its preparation method, so as to improve the axial compressive bearing capacity, ductility and seismic performance of the polymer concrete column. The specific technical solution is as follows.
[0015] A multi-confined polymer concrete column with FRP-bamboo wound tubes, comprising:
[0016] The core concrete column is cast from lithium slag geopolymer concrete.
[0017] Bamboo-wound tubes are wrapped around the outside of the core concrete column. The bamboo-wound tubes are formed by directional winding of bamboo strips and curing with adhesive.
[0018] An FRP composite layer is wrapped around the outer surface of the bamboo-wound pipe. The FRP composite layer is composed of FRP fiber cloth and epoxy resin adhesive, which improves the compressive strength and ductility of the concrete column through multiple constraints.
[0019] The core concrete column, bamboo-wound pipe, and FRP composite layer are closely bonded together to form a multi-restraint structure, which together bears the axial load.
[0020] Furthermore, the lithium slag geopolymer concrete is formed by mixing and stirring lithium slag, fly ash, slag, alkali activator and fine aggregate, wherein the mass substitution rate of lithium slag is 10%~30%.
[0021] Furthermore, the thickness of the bamboo-wound tube is 5mm to 20mm; the material of the FRP composite layer is carbon fiber (CFRP), glass fiber (GFRP), or basalt fiber (BFRP).
[0022] Furthermore, the bamboo-wound tube is prepared using a continuous bamboo strip spiral winding process, and is impregnated with a thermosetting resin adhesive and cured.
[0023] Furthermore, the FRP composite layer is made of unidirectional fiber cloth, which is wound 2 to 5 layers around the column and cured with epoxy resin impregnation adhesive to form a constraint layer.
[0024] A method for preparing an FRP-bamboo-wound tube multi-confined polymer concrete column includes the following steps:
[0025] (1) Preparation of core concrete column: According to the design mix ratio, lithium slag, fly ash, slag, alkali activator and fine aggregate are mixed evenly, poured into the cylindrical mold and vibrated to compact, and then cured according to standard to obtain the geopolymer concrete core.
[0026] (2) Bamboo winding pipe preparation: The surface of the cured geopolymer concrete core is coated with epoxy resin adhesive, and bamboo strips are impregnated with thermosetting resin and wound around the outside of the core through a directional winding process, and cured to form a bamboo winding pipe.
[0027] (3) FRP composite layer winding: Apply epoxy resin adhesive to the surface of bamboo winding pipe, and wind FRP fiber cloth evenly in the circumferential direction for 2 to 5 layers. After curing, an FRP composite layer is formed, and finally an FRP-bamboo winding pipe multi-constrained polymer concrete column is obtained.
[0028] Beneficial effects:
[0029] (1) The present invention effectively improves the axial compressive bearing capacity and ductility of the geopolymer concrete column by using the composite constraint of bamboo winding tube and FRP fiber, suppresses the brittle failure characteristics of the concrete column under axial compressive state, and improves the safety and reliability of the structure.
[0030] (2) The application of lithium slag geopolymer concrete not only realizes the efficient resource utilization of industrial solid waste, but also reduces the carbon emissions of concrete, which meets the development needs of national green building.
[0031] (3) The introduction of bamboo-wound tubes fully utilizes the advantages of bamboo's wide availability, renewability, and low price, reducing the overall cost of the structure. The synergistic effect of FRP and bamboo-wound tubes compensates for the deficiencies of insufficient bamboo stiffness and high FRP cost, achieving a good balance between economy and performance. Attached Figure Description
[0032] Figure 1 This is a three-dimensional schematic diagram of the entire invention.
[0033] serial number:
[0034] 1. Geopolymer concrete core: solid cylindrical base, serving as the core load-bearing unit of the column, with dense and uniform material.
[0035] 2. Bamboo-wound tube: It is formed by circumferential winding and tightly wraps around the outer periphery of the geopolymer concrete core 1. The tube wall thickness is uniform and presents a continuous bamboo fiber winding texture.
[0036] 3. FRP composite layer: It is a constraint layer formed by circumferential winding and solidification on the outer surface of the bamboo winding tube 2. It is a fiber cloth impregnated with resin and cured. It is firmly bonded to the bamboo winding tube and exhibits the circumferential winding layered characteristics of the fiber. Detailed Implementation
[0037] To better understand the present invention, preferred embodiments are described below. These preferred embodiments are used to illustrate and explain the invention, but are not intended to limit the invention. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention. The bamboo-wound tube is formed by directional winding and curing of bamboo fiber and thermosetting resin. Bamboo is widely available and renewable. The FRP composite layer is selected from one or more of carbon fiber, glass fiber, or basalt fiber, and its synergistic effect with the bamboo-wound tube can significantly improve the confinement effect of the core concrete. In the following embodiments, epoxy resin is used as the resin adhesive, and the mass ratio of resin to curing agent is 3:1. This ratio provides superior curing effect and bonding strength.
[0038] Example 1
[0039] This embodiment provides an FRP-bamboo-wound tube multi-constrained polymer concrete column and its preparation method.
[0040] The composition of the FRP-bamboo-wound tube multi-constrained polymer concrete column in this embodiment is as follows: a geopolymer concrete core (made from a mixture of lithium slag, fly ash, slag, alkali activator, and fine aggregate, wherein the lithium slag mass substitution rate is 20%), a bamboo-wound tube (10mm thick, made using a continuous bamboo strip spiral winding process, and cured by thermosetting resin impregnation), and an FRP composite layer (made of carbon fiber reinforced polymer CFRP, wound in three layers circumferentially, with an overlap length not less than one-third of the fiber cloth circumference). The specific preparation steps are as follows:
[0041] Step 1: Weigh lithium slag, fly ash, slag, alkali activator and fine aggregate according to the design mix ratio, mix evenly and pour into a cylindrical mold, vibrate to compact, and perform standard curing for 28 days to obtain the geopolymer concrete core.
[0042] Step 2: Apply epoxy resin to the surface of the cured geopolymer concrete core, and then wrap bamboo fiber impregnated with resin around the outside of the core using a directional winding process, curing to form a 10mm thick bamboo winding tube.
[0043] Step 3: Apply epoxy resin to the surface of the bamboo-wound pipe, and then wrap CFRP fiber cloth evenly in three layers in a circumferential direction. After curing, an FRP composite layer is formed, and finally an FRP-bamboo-wound pipe multi-constrained polymer concrete column is obtained.
[0044] Example 2
[0045] This embodiment provides an FRP-bamboo-wound tube multi-constrained polymer concrete column and its preparation method.
[0046] The composition of the FRP-bamboo-wound tube multi-confined geolithic concrete column in this embodiment is as follows: a geolithic concrete core (lithium slag mass replacement rate of 30%), a bamboo-wound tube (15mm thick), and an FRP composite layer (using glass fiber reinforced polymer GFRP, wound 5 layers circumferentially). The specific preparation steps are as follows:
[0047] Step 1: Weigh lithium slag, fly ash, slag, alkali activator and fine aggregate (lithium slag replacement rate 30%) according to the design mix ratio, mix evenly and pour into a cylindrical mold, vibrate to compact, and cure for 28 days to obtain the geopolymer concrete core.
[0048] Step 2: Apply epoxy resin to the surface of the cured geopolymer concrete core, and then wrap bamboo fiber impregnated with resin around the outside of the core using a directional winding process, curing to form a 15mm thick bamboo winding tube.
[0049] Step 3: Apply epoxy resin to the surface of the bamboo-wound pipe, and then wrap 5 layers of GFRP fiber cloth evenly in a circumferential direction. After curing, an FRP composite layer is formed, and finally an FRP-bamboo-wound pipe multi-constrained polymer concrete column is obtained.
[0050] Comparative Example 1
[0051] This comparative example provides a single bamboo-wound tube geopolymer concrete column without FRP constraint and its preparation method.
[0052] The composition of this comparative example geopolymer concrete column is as follows: a geopolymer concrete core (lithium slag mass replacement rate of 20%), a bamboo-wound tube (10mm thick), and no outer FRP composite layer. The specific preparation steps are as follows:
[0053] The only difference between this comparative example and Example 1 is that an outer FRP composite layer is not included. All other materials, mixing ratios, curing conditions, and winding processes are the same as in Example 1. The specific preparation steps are as follows:
[0054] Step 1: Prepare the geopolymer concrete core according to the mix proportion of Example 1, and cure it for 28 days under standard conditions;
[0055] Step 2: Apply epoxy resin to the surface of the cured geopolymer concrete core. Then, impregnate bamboo fiber with resin and wind it around the outside of the core using a directional winding process. After curing, a 10mm thick bamboo winding tube is formed, resulting in a single bamboo winding tube constrained geopolymer concrete column.
[0056] The axial compression properties of the FRP-bamboo-wound tube-confined polymer concrete columns prepared in Example 1, Example 2, and Comparative Example 1 were tested, and the results are shown in the table below:
[0057] Sample number Axial compression bearing capacity (kN) Ductility coefficient Destruction Mode Example 1 285.6 4.2 Gradual failure; the bamboo tube continues to bear pressure after the FRP fractures. Example 2 312.4 5.1 Progressive destruction and multiple constraints have significant effects. Comparative Example 1 198.3 2.4 Brittle fracture; the load-bearing capacity drops sharply after the bamboo tube cracks.
[0058] As can be seen from the table above, the axial compressive bearing capacity and ductility coefficient of the FRP-bamboo-wound tube multi-constrained polymer-concrete column in this embodiment are significantly higher than those of the comparative example constrained by a single bamboo-wound tube. Specifically, the bearing capacity of Example 2 is increased by 57.5% and the ductility coefficient by 112.5% compared to Comparative Example 1, indicating that the multi-constraint structure formed by FRP and bamboo-wound tube can effectively improve the brittle failure characteristics of polymer-concrete columns and enhance the safety and reliability of the structure. Both Examples 1 and 2 exhibit progressive failure modes, demonstrating that the multi-constraint structure has good synergistic performance and can be widely applied in structural engineering such as bridges, buildings, and precast components.
Claims
1. A multi-confined polymer concrete column with FRP-bamboo wound tube, characterized in that, include: Geopolymer concrete core; Bamboo-wound tube, wherein the bamboo-wound tube is sleeved on the outer surface of the geopolymer concrete core; An FRP composite layer is wound and fixed to the outer surface of the bamboo winding tube; The bamboo-wound tube is formed by directional winding and curing of bamboo fiber and thermosetting resin; the FRP composite layer is formed by impregnation and curing of fiber-reinforced polymer cloth and resin; the bamboo-wound tube and the FRP composite layer together provide multiple constraints for the geopolymer concrete core.
2. The FRP-bamboo-wound tube multi-confined polymer concrete column according to claim 1, characterized in that, The geopolymer concrete core is prepared by partially or completely replacing fly ash with lithium slag; the alkali activator of the geopolymer concrete core is in liquid or solid form.
3. The FRP-bamboo-wound tube multi-confined polymer concrete column according to claim 1, characterized in that, The thickness of the bamboo-wound tube is 5mm to 20mm.
4. The FRP-bamboo-wound tube multi-confined polymer concrete column according to claim 1, characterized in that, The FRP composite layer is composed of one or more of carbon fiber reinforced polymer (CFRP), glass fiber reinforced polymer (GFRP), or basalt fiber reinforced polymer (BFRP).
5. The FRP-bamboo-wound tube multi-confined polymer concrete column according to claim 1, characterized in that, Both the bamboo-wound tube and the FRP composite layer are arranged in a circumferential manner, and the FRP composite layer and the bamboo-wound tube are firmly bonded together by a resin adhesive layer.
6. The method for preparing an FRP-bamboo-wound tube multi-confined polymer concrete column according to any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Prepare the geopolymer concrete core and cure it to shape; S2. Bamboo fiber is impregnated with resin and then wound around the outside of the cured geopolymer concrete core through a directional winding process, and then cured to form a bamboo winding pipe. S3. Apply resin adhesive to the surface of the bamboo wound tube and wrap it with FRP fiber cloth to form an FRP composite layer. After curing, an FRP-bamboo wound tube multi-constraint structure is formed.
7. The preparation method according to claim 6, characterized in that, In step S3, the number of FRP fiber cloth layers is 1 to 5, and the overlap length of the FRP fiber cloth during the winding process is not less than one-third of the circumference of the fiber cloth.
8. The preparation method according to claim 6, characterized in that, The resin adhesive is selected from epoxy resin or vinyl resin, and the mass ratio of resin to curing agent is 2:1 to 4:1.